IDH1 and astrocytoma (excluding glioblastoma): The 1p19q molecular alteration is a defining event caused by an unbalanced whole-arm translocation between chromosome 1 and chromosome 19, and has prognostic and predictive value as patients enjoy better overall survival and are more responsive to treatment with chemotherapy than comparable grade astrocytomas.56–58 The biologic and metabolic consequences of 1p19 codeletion, however, remain unclear although they do not induce an obvious oncometabolite like 2HG with IDH mutation.